A method for identifying crude oil types based on two-dimensional gas chromatography-time-of-flight mass spectrometry.

Abstract

This invention provides a method for identifying crude oil types based on two-dimensional gas chromatography-time-of-flight mass spectrometry (GC-TOF-MS). The method includes: dissolving the crude oil sample to be identified using a diluent, then adding a 5α-androstane standard to the system to obtain the crude oil sample; performing chromatographic analysis of the crude oil sample using GC-TOF-MS; denoting the ratio of the sum of the weights of n-alkanes, isoalkanes, monocyclic alkanes, bicyclic alkanes, tricyclic alkanes, tetracyclic alkanes, and pentacyclic alkanes in the crude oil sample to the weight of the crude oil sample to be identified as S; denoting the ratio of the sum of the weights of monocyclic alkanes, bicyclic alkanes, tricyclic alkanes, tetracyclic alkanes, and pentacyclic alkanes in the crude oil sample to the weight of the crude oil sample to be identified as N; and identifying the type of crude oil sample based on the ratio of S to N. This method provides a new approach for the precise identification of naphthenic crude oil and the estimation of naphthenic crude oil reserves.

Description

Technical Field

[0001] This invention relates to the field of petroleum geological exploration technology, and more specifically, to a method for identifying crude oil types based on full two-dimensional gas chromatography-time-of-flight mass spectrometry. Background Technology

[0002] Naphthenic crude oil is a scarce petroleum resource containing a high proportion of cycloalkane components, and the cycloalkane content in crude oil directly affects its quality. Currently, the industry mainly employs four methods for the quantitative identification of cycloalkane crude oil: the key fraction method, the characteristic factor K classification method, the crude oil carbon form content calculation method, and gas chromatography / mass spectrometry (GC / MS) quantification. Among these methods, the key fraction method is relatively complex to operate, and because impurities such as alkanes and aromatics are mixed in during distillation, it cannot accurately reflect the cycloalkanes content in crude oil. The characteristic factor K classification method for determining the average boiling point of crude oil is difficult and cannot accurately characterize the composition of crude oil. The calculation method for the carbon form content of crude oil is cumbersome, and the calculated carbon form content is a theoretical value. Hydrocarbons are composed of both carbon and hydrogen atoms; calculating only the carbon atom content cannot represent the cycloalkanes content, limiting its applicability. Gas chromatography / mass spectrometry (GC / MS) for quantifying hydrocarbons of different structures in crude oil often results in baseline elevation and "bulges" during one-dimensional chromatographic analysis, making it difficult to separate compounds within these "bulges" and thus hindering accurate characterization and quantification. When using mass spectrometry, the different mass spectral signal response factors for different hydrocarbon structures result in only semi-quantitative analysis of hydrocarbons. Therefore, using GC / MS to quantify the cycloalkanes content in crude oil has significant limitations. Previous studies have suggested that cycloalkanes are distributed in crude oils with densities greater than 0.93 g / cm³. 3 While heavy oil is often included, a portion of medium-grade crude oil is actually naphthenic. Because naphthenic crude oil constitutes a smaller proportion of medium-grade crude oil, identifying it is more challenging. Current technologies cannot accurately quantify naphthenic hydrocarbons in crude oil, making it even more difficult to quantitatively analyze them from the relatively small proportion of medium-grade crude oil. This limits the scope of naphthenic crude oil identification and restricts the extraction of naphthenic crude oil.

[0003] In summary, existing technologies struggle to accurately quantify cycloalkanes in crude oil, suffering from limitations such as complex operation, narrow applicability, or poor separation efficiency. Therefore, it is necessary to provide a new analytical method to address these issues and broaden the identification range of cycloalkanes in crude oil. Summary of the Invention

[0004] The main objective of this invention is to provide a method for identifying crude oil types based on two-dimensional gas chromatography-time-of-flight mass spectrometry, in order to solve the problem of accurate quantification of cycloalkanes in crude oil in the prior art.

[0005] To achieve the above objectives, according to one aspect of the present invention, a method for identifying crude oil types based on two-dimensional gas chromatography-time-of-flight mass spectrometry is provided, characterized in that the method comprises: crude oil sample preparation: dissolving the crude oil sample to be identified using a diluent, and then adding 5α-androstane standard to the system to obtain a crude oil sample; testing: introducing the crude oil sample into a two-dimensional gas chromatography-time-of-flight mass spectrometer; and qualitatively identifying the peak positions of 5α-androstane, n-alkanes, isoalkanes, monocyclic alkanes, bicyclic alkanes, tricyclic alkanes, tetracyclic alkanes, and pentacyclic alkanes in the crude oil sample based on the time-of-flight mass spectrometry. The content of n-alkanes, isoalkanes, monocyclic alkanes, bicyclic alkanes, tricyclic alkanes, tetracyclic alkanes, and pentacyclic alkanes with a signal-to-noise ratio greater than 100 in crude oil samples was quantitatively analyzed based on the peak area of ​​5α-androstane in two-dimensional gas chromatography. Identification: The ratio of the sum of the weights of n-alkanes, isoalkanes, monocyclic alkanes, bicyclic alkanes, tricyclic alkanes, tetracyclic alkanes, and pentacyclic alkanes in the crude oil sample to the weight of the crude oil sample to be identified was denoted as S; the ratio of the sum of the weights of monocyclic alkanes, bicyclic alkanes, tricyclic alkanes, tetracyclic alkanes, and pentacyclic alkanes in the crude oil sample to the weight of the crude oil sample to be identified was denoted as N.

[0006] When S≥50% and N≤30%, the crude oil sample to be identified is paraffinic crude oil;

[0007] When S≥50% and 30%<N<40%, the crude oil sample to be identified is intermediate crude oil.

[0008] When S≥50% and N≥40%, the crude oil sample to be identified is a naphthenic crude oil.

[0009] When S < 50% and N < 25%, the crude oil sample to be identified is an aromatic-asphalt type crude oil.

[0010] When S < 50% and N ≥ 25%, the crude oil sample to be identified is an aromatic-cycloalkane type crude oil.

[0011] Furthermore, in the preparation of crude oil samples, the weight of the crude oil sample to be identified is 5 to 15 mg per 1 ml of diluent.

[0012] Furthermore, in the preparation of crude oil samples, the weight of 5α-androstane standard is 0.001–0.01 mg per 1 ml of diluent.

[0013] Furthermore, the diluent is selected from n-hexane and / or dichloromethane, more preferably dichloromethane.

[0014] Furthermore, the full two-dimensional gas chromatograph has two columns with different polarities, each independently selected from either a DB-Petro column or a DB-17HT column.

[0015] Furthermore, the detector in the all-two-dimensional gas chromatograph is a flame ionization detector.

[0016] Furthermore, the modulator of the full two-dimensional gas chromatograph adopts a dual-nozzle thermal modulator; more preferably, the modulation cycle of the modulator is 8.0 to 10.0 s, and the hot blowing time is 2.0 to 3.0 s.

[0017] Furthermore, the DB-Petro column has a length of 50–60 m, an outer diameter of 0.2–0.3 mm, an inner diameter of 0.1–0.2 mm, and a coating thickness of 0.1–0.5 μm; the DB-17HT column has a length of 2.5–3.0 m, an outer diameter of 0.1–0.2 mm, an inner diameter of 0.1–0.2 mm, and a coating thickness of 0.1–0.5 μm.

[0018] Furthermore, the one-dimensional column of the all-two-dimensional gas chromatograph is a DB-Petro column, and the two-dimensional column is a DB-17HT column. The temperature program for the one-dimensional column is as follows: hold at an initial temperature of 60–80℃ for 0.1–0.2 min, increase to 290–300℃ at a rate of 2–3℃ / min, hold for 0.1–0.2 min, and then increase to 300–310℃ at a rate of 0.1–0.2℃ / min, hold for 8–10 min. The temperature program for the two-dimensional column is as follows: hold at an initial temperature of 70–90℃ for 0.1–0.2 min, increase to 290–300℃ at a rate of 2–3℃ / min, hold for 0.1–0.2 min, and then increase to 300–310℃ at a rate of 0.1–0.2℃ / min, hold for 8–10 min. The temperature is increased to 300–310℃ at a rate of ℃ / min, held for 0.1–0.2 min, then increased to 310–320℃ at a rate of 0.1–0.2℃ / min, and held for 8–10 min. The modulation temperature program is as follows: at an initial temperature of 120–130℃, it is held for 0.1–0.2 min, then increased to 330–350℃ at a rate of 2.0–3.0℃ / min, held for 0.1–0.3 min, then increased to 340–360℃ at a rate of 0.2℃ / min, and held for 10 min. The modulator cycle is 7–9 s, of which 1–3 s is the heat blowing time.

[0019] Furthermore, the injection port temperature of the full two-dimensional gas chromatograph is 300–310°C.

[0020] Furthermore, the injection volume of crude oil samples was 1.0–1.2 μL.

[0021] Furthermore, the carrier gas flow rate of the two-dimensional gas chromatograph is 1.4–1.6 mL / min.

[0022] Furthermore, the carrier gas is helium.

[0023] Furthermore, the weight content of components with a density greater than 0.87 g / cm3 in the crude oil sample to be identified is 45–55 wt%.

[0024] Applying the technical solution of this invention, a method for identifying crude oil types based on two-dimensional gas chromatography-time-of-flight mass spectrometry (GC-MS / MS) is developed. Utilizing the high resolution, large peak capacity, good sensitivity, group separation, and tile effect of GC-MS, it maximizes the separation of n-alkanes, isoalkanes, monocyclic alkanes, bicyclic alkanes, tricyclic alkanes, tetracyclic alkanes, pentacyclic alkanes, and other components. Simultaneously, the addition of a suitable internal standard (5α-androstane) allows for accurate quantitative analysis of various compounds in the crude oil. Its quantitative precision and accuracy are far superior to one-dimensional gas chromatography, effectively eliminating co-distillation between different series of compounds. A single injection can separate almost all hydrocarbon compounds in the crude oil. This invention analyzes the content of n-alkanes, isoalkanes, monocyclic alkanes, bicyclic alkanes, tricyclic alkanes, tetracyclic alkanes, and pentacyclic alkanes in crude oil with a signal-to-noise ratio greater than 100. This eliminates the influence of other impurities in the crude oil or instrument noise on the accuracy of the n-alkanes, isoalkanes, monocyclic alkanes, bicyclic alkanes, tricyclic alkanes, tetracyclic alkanes, and pentacyclic alkanes content. Furthermore, based on the determination of the content of these substances in crude oil and the S / N ratio, this invention can identify the type of crude oil sample, providing a new approach for the precise identification of naphthenic crude oil and the estimation of naphthenic crude oil reserves. Attached Figure Description

[0025] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0026] Figure 1 A three-dimensional stereoscopic view of a crude oil sample obtained by full two-dimensional gas chromatography in Embodiment 1 of the present invention is shown.

[0027] Figure 2 The image shows a full two-dimensional gas chromatograph of different components in a crude oil sample according to Example 1 of the present invention.

[0028] Figure 3 A three-dimensional stereoscopic view of a crude oil sample obtained by full two-dimensional gas chromatography in Embodiment 2 of the present invention is shown.

[0029] Figure 4 The image shows a dot matrix of different components in a crude oil sample from Example 2 of the present invention using a full two-dimensional gas chromatograph.

[0030] Figure 5 A three-dimensional stereoscopic view of the crude oil sample of Embodiment 3 of the present invention, obtained by full two-dimensional gas chromatography, is shown.

[0031] Figure 6 The image shows a full two-dimensional gas chromatograph of different components in a crude oil sample according to Example 3 of the present invention.

[0032] Figure 7 A three-dimensional stereoscopic view of the crude oil sample of Embodiment 4 of the present invention, obtained by full two-dimensional gas chromatography, is shown.

[0033] Figure 8 The image shows a full two-dimensional gas chromatograph of different components in a crude oil sample according to Example 4 of the present invention.

[0034] Figure 9 This is an analysis and identification diagram of crude oil types in an embodiment of the present invention.

[0035] The above-mentioned figures include the following reference numerals: Region 1 is paraffinic crude oil, Region 2 is intermediate crude oil, Region 3 is naphthenic crude oil, Region 4 is aromatic-asphalt type crude oil, and Region 5 is aromatic-naphthenic crude oil. Detailed Implementation

[0036] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0037] The main components of crude oil include the following: saturated hydrocarbons, including normal and isoalkanes (paraffinic hydrocarbons) and cycloalkanes; aromatic hydrocarbons, including pure aromatic hydrocarbons, cycloalkanes, and cyclic sulfur-containing compounds; and resins and asphaltenes, composed of high-molecular-weight polycyclic compounds containing nitrogen, sulfur, and oxygen in crude oil. This invention classifies crude oil based on the different proportions of each component as follows:

[0038] Paraffinic crude oil: Paraffinic crude oil is crude oil mainly containing paraffinic hydrocarbons. It has a relatively low density, high wax content, high pour point, and low sulfur and gum content.

[0039] Naphthenic crude oil: Naphthenic crude oil is a type of crude oil with a high content of naphthenes. Gasoline produced from naphthenic crude oil has a high octane number, diesel has a low cetane number, lubricating oil fraction has little or no wax content, a low pour point, a low viscosity index, and the residual oil contains more asphalt.

[0040] Intermediate crude oil: A type of crude oil whose properties fall between those of paraffinic crude oil and naphthenic crude oil.

[0041] Aromatic-asphalt type crude oil: Aromatic-asphalt type crude oil is a type of crude oil with a high content of aromatic hydrocarbons. It is heavy and viscous, and the content of gum and asphaltenes can be as high as 25%.

[0042] Aromatic-cycloalkane type crude oil: Aromatic-cycloalkane type crude oil is a type of crude oil mainly containing aromatic hydrocarbons and cycloalkanes. It is heavy and viscous.

[0043] As described in the background section of this application, existing technologies suffer from difficulties in accurately quantifying cycloalkanes in crude oil. To address this issue, this application provides a method for identifying crude oil types based on two-dimensional gas chromatography-time-of-flight mass spectrometry (GC-TOF-MS), comprising: crude oil sample preparation: dissolving the crude oil sample to be identified using a diluent, and then adding 5α-androstane standard to the system to obtain a crude oil sample; testing: introducing the crude oil sample into a two-dimensional GC-TOF-MS spectrometer, and qualitatively determining the peak positions of 5α-androstane, n-alkanes, isoalkanes, monocyclic alkanes, bicyclic alkanes, tricyclic alkanes, tetracyclic alkanes, and pentacyclic alkanes in the crude oil sample based on the time-of-flight mass spectrometry; quantitatively analyzing the content of n-alkanes, isoalkanes, monocyclic alkanes, bicyclic alkanes, tricyclic alkanes, tetracyclic alkanes, and pentacyclic alkanes with a signal-to-noise ratio greater than 100 in the crude oil sample based on the peak area of ​​5α-androstane in the GC-MS; identification: identifying the content of 5α-androstane, isoalkanes, monocyclic alkanes, bicyclic alkanes, tricyclic alkanes, tetracyclic alkanes, and pentacyclic alkanes in the crude oil sample based on the peak area of ​​5α-androstane in the GC-MS; and further identifying the content of 5α-androstane, isoalkanes, monocyclic alkanes, bicyclic alkanes, tricyclic alkanes, tetracyclic alkanes, and pentacyclic alkanes in the crude oil sample based on the peak area of ​​5α-androstane in the GC-MS. The ratio of the sum of the weights of alkanes, isoalkanes, monocycloalkanes, bicycloalkanes, tricycloalkanes, tetracycloalkanes, and pentacycloalkanes to the weight of the crude oil sample to be identified is denoted as S (saturated hydrocarbon content); the ratio of the sum of the weights of monocycloalkanes, bicycloalkanes, tricycloalkanes, tetracycloalkanes, and pentacycloalkanes in the crude oil sample to the weight of the crude oil sample to be identified is denoted as N (cycloalkane content); when S ≥ 50% and N ≤ 30%, the crude oil sample to be identified is paraffinic crude oil; when S ≥ 50% and 30% < N < 40%, the crude oil sample to be identified is intermediate crude oil; when S ≥ 50% and N ≥ 40%, the crude oil sample to be identified is cycloalkane-type crude oil; when S < 50% and N < 25%, the crude oil sample to be identified is aromatic-asphalt type crude oil; when S < 50% and N ≥ 25%, the crude oil sample to be identified is aromatic-cycloalkane type crude oil.

[0044] This invention proposes a method for identifying crude oil types based on two-dimensional gas chromatography-time-of-flight mass spectrometry, which solves the problem of inaccurate quantification of cycloalkanes in crude oil in existing technologies, mainly for the following reasons:

[0045] Firstly, existing technologies such as the key fraction method, the characteristic factor K classification method, and the crude oil carbon form content calculation method all establish a relationship between crude oil density, boiling point, refractive index, and cycloalkanes, using cumbersome empirical calculation formulas to characterize cycloalkane content. However, the physical properties of crude oil are the result of the combined effects of saturated hydrocarbons, aromatics, asphaltenes, and non-hydrocarbons, and these methods cannot accurately reflect the cycloalkane content in crude oil. The method of this invention, by adding standard substances to crude oil, eliminates the need for cumbersome empirical calculation formulas. It uses time-of-flight mass spectrometry coupled with two-dimensional gas chromatography to qualitatively analyze the compounds in the crude oil sample according to their molecular weight, identifying 5α-androstanes, n-alkanes, isoalkanes, and cycloalkanes. Simultaneously, based on the ratio of the peak areas of n-alkanes, isoalkanes, monocycloalkanes, bicycloalkanes, tricycloalkanes, tetracycloalkanes, and pentacycloalkanes in a two-dimensional gas chromatograph to the peak area of ​​the 5α-androstane standard, along with the mass ratio of the crude oil sample to the 5α-androstane standard and the relative correction factor, the content of n-alkanes, isoalkanes, monocycloalkanes, bicycloalkanes, tricycloalkanes, tetracycloalkanes, and pentacycloalkanes in crude oil can be accurately quantified. This method not only significantly improves the efficiency of evaluating cycloalkane-type crude oils but also offers higher accuracy.

[0046] Secondly, compared with existing methods for quantifying cycloalkanes in crude oil using chromatography / mass spectrometry, this invention uses fewer types of standard substances and eliminates the need for complex pretreatment of crude oil, thus solving the problem of qualitative and quantitative analysis of indistinguishable complex mixtures (UCMs). The inventors discovered that the molecular structure of the 5α-androstane standard differs from that of n-alkanes, isoalkanes, and cycloalkanes in crude oil. Furthermore, the peak position of 5α-androstane in a two-dimensional gas chromatograph differs from that of n-alkanes, isoalkanes, and cycloalkanes in crude oil, thus not interfering with the separation of substances in the crude oil. Simultaneously, the 5α-androstane standard exhibits rapid and sensitive response in a two-dimensional gas chromatograph.

[0047] In summary, this invention provides a method for identifying crude oil types based on two-dimensional gas chromatography-time-of-flight mass spectrometry. Utilizing the high resolution, large peak capacity, good sensitivity, group separation, and tile effect of two-dimensional gas chromatography, it maximizes the separation of n-alkanes, isoalkanes, monocyclic alkanes, bicyclic alkanes, tricyclic alkanes, tetracyclic alkanes, pentacyclic alkanes, and other components. Simultaneously, the addition of a suitable internal standard (5α-androstane) allows for accurate quantitative analysis of various compounds in the crude oil. Its quantitative precision and accuracy are far superior to one-dimensional gas chromatography, effectively eliminating co-distillation between different compound series. A single injection can separate almost all hydrocarbon compounds in the crude oil. This invention analyzes the content of n-alkanes, isoalkanes, monocyclic alkanes, bicyclic alkanes, tricyclic alkanes, tetracyclic alkanes, and pentacyclic alkanes in crude oil with a signal-to-noise ratio greater than 100. This eliminates the influence of other impurities in the crude oil or instrument noise on the accuracy of the n-alkanes, isoalkanes, monocyclic alkanes, bicyclic alkanes, tricyclic alkanes, tetracyclic alkanes, and pentacyclic alkanes content. Furthermore, based on the determination of the content of these substances in crude oil and the S / N ratio, this invention can identify the type of crude oil sample, providing a new approach for the precise identification of naphthenic crude oil and the estimation of naphthenic crude oil reserves.

[0048] In a preferred embodiment, during crude oil sample preparation, the weight of the crude oil sample to be identified is 5-15 mg per 1 ml of diluent. This invention reduces the viscosity of the crude oil by using a diluent to dilute the crude oil sample, and by controlling the concentration of the crude oil sample in the diluent, it enables the crude oil sample to exhibit good peak shape in a two-dimensional gas chromatograph while maintaining high sensitivity.

[0049] In a preferred embodiment, in the preparation of the crude oil sample, the weight of the 5α-androstane standard is 0.001–0.01 mg per 1 ml of diluent. This invention, by adding 5α-androstane to the crude oil sample to be identified, utilizes the fact that the molecular structure of the 5α-androstane standard differs from that of the n-alkanes, isoalkanes, and cycloalkanes in the crude oil. Consequently, the peak position of 5α-androstane in a two-dimensional gas chromatograph differs from that of the n-alkanes, isoalkanes, and cycloalkanes in the crude oil, thus not interfering with the separation of various substances in the crude oil. Based on the amount of 5α-androstane added and the peak area, the content of n-alkanes, isoalkanes, monocyclic alkanes, bicyclic alkanes, tricyclic alkanes, tetracyclic alkanes, and pentacyclic alkanes in the crude oil to be identified can be accurately and quantitatively analyzed. Meanwhile, this invention limits the concentration of 5α-androstane standard in crude oil samples, giving it a better response value and excellent peak shape in the chromatograph, preventing interference with the peak shapes of other substances, and enabling more accurate quantitative analysis of the content of each component in crude oil.

[0050] In a preferred embodiment, during the preparation of the crude oil sample, after adding the 5α-androstane standard, ultrasonic vibration is employed, followed by a period of settling to obtain the crude oil sample. Preferably, the ultrasonic vibration time is 5–20 min, and the settling time is 0.3–0.5 h. This method allows for thorough mixing of the standard substance and crude oil, resulting in higher accuracy and reliability during detection and analysis.

[0051] To further enhance the peak shape and sensitivity of crude oil samples in a two-dimensional gas chromatograph, the diluent is preferably selected from n-hexane and / or dichloromethane, more preferably dichloromethane. Because dichloromethane exhibits excellent similarity-to-miscibility with crude oil, it can dissolve crude oil more uniformly. Furthermore, dichloromethane does not interfere with the components in crude oil during chromatography, resulting in good separation of the components in the crude oil. Additionally, dichloromethane has a fast elution time, which can significantly shorten the analysis time.

[0052] In a preferred embodiment, the two-dimensional gas chromatograph has two columns with different polarities, each independently selected from either a DB-Petro column or a DB-17HT column. This invention uses these two columns with different polarities: a non-polar DB-Petro column and a strongly polar DB-17HT column. Through the difference in polarity between the two columns, saturated alkane components (such as n-alkanes, isoalkanes, monocyclic alkanes, bicyclic alkanes, tricyclic alkanes, tetracyclic alkanes, and pentacyclic alkanes) in the crude oil sample are better separated from aromatic hydrocarbon components. The DB-Petro column can effectively separate components with different boiling points in the crude oil sample, while the DB-17HT column can effectively separate co-distilled components with similar boiling points but different polarities in the crude oil sample.

[0053] In a preferred embodiment, the detector of the two-dimensional gas chromatograph is a flame ionization detector (FID). The FID used in this invention exhibits high sensitivity to alkanes in crude oil, enabling more accurate quantification of cycloalkanes in crude oil samples and achieving identification of crude oil types.

[0054] To achieve better separation of components in crude oil samples, the modulator of the two-dimensional gas chromatograph uses a dual-nozzle thermal modulator; more preferably, the modulation cycle of the modulator is 8.0 to 10.0 s, and the hot blowing time is 2.0 to 3.0 s.

[0055] In a preferred embodiment, the DB-petro column has a length of 50–60 m, an outer diameter of 0.2–0.3 mm, an inner diameter of 0.1–0.2 mm, and a coating thickness of 0.1–0.5 μm; the DB-17HT column has a length of 2.5–3.0 m, an outer diameter of 0.1–0.2 mm, an inner diameter of 0.1–0.2 mm, and a coating thickness of 0.1–0.5 μm. The coating of the DB-petro column is dimethyl polysiloxane, and the coating of the DB-17HT column is a high-temperature resistant polyimide coating. This invention limits the column length, diameter, and coating thickness within the above-mentioned ranges, maximizing the separation of n-alkanes, isoalkanes, monocyclic alkanes, bicyclic alkanes, tricyclic alkanes, tetracyclic alkanes, and pentacyclic alkanes from other components, making the quantification of cycloalkanes in crude oil more accurate and reliable.

[0056] In a preferred embodiment, the one-dimensional column of the two-dimensional gas chromatograph is a DB-1 column, and the two-dimensional column is a DB-17HT column. The temperature program for the one-dimensional column is as follows: hold at an initial temperature of 60–80°C for 0.1–0.2 min, increase the temperature to 290–300°C at a rate of 2–3°C / min, hold for 0.1–0.2 min, and then increase the temperature to 300–310°C at a rate of 0.1–0.2°C / min, hold for 8–10 min. The temperature program for the two-dimensional column is as follows: hold at an initial temperature of 70–90°C for 0.1–0.2 min, and then increase the temperature to 290–300°C at a rate of 2–3°C / min, hold for 0.1–0.2 min, and then increase the temperature to 300–310°C at a rate of 0.1–0.2°C / min, hold for 8–10 min. The temperature is increased to 300-310℃ at a rate of ~3℃ / min, held for 0.1-0.2 min, then increased to 310-320℃ at a rate of 0.1-0.2℃ / min, and held for 8-10 min. The modulation temperature increase program is as follows: at an initial temperature of 120-130℃, it is held for 0.1-0.2 min, then increased to 330-350℃ at a rate of 2.0-3.0℃ / min, held for 0.1-0.3 min, then increased to 340-360℃ at a rate of 0.2℃ / min, and held for 10 min. The modulator cycle is 7-9 s, of which 1-3 s is the heat blowing time.

[0057] This invention employs a staged temperature program for the one-dimensional chromatographic column, two-dimensional chromatographic column, and modulator, extending the analysis time for different components in crude oil and maximizing the elution of all components, thereby improving the accuracy of cycloalkanes content in crude oil. Furthermore, the temperature program utilizes two different heating rates: first, a higher heating rate of 2–3 °C / min is used, followed by a lower heating rate of 0.1–0.2 °C. Compared to a single-stage heating method, this offers advantages such as higher resolution, easier qualitative analysis, and more accurate integration.

[0058] To further improve the accuracy of cycloalkanes determination in crude oil samples, the injection port temperature of the two-dimensional gas chromatograph is preferably 300–310°C, and the injection volume of the crude oil sample is preferably 1.0–1.2 μL; preferably, the two-dimensional gas chromatograph uses a splitless injection method.

[0059] In a preferred embodiment, the carrier gas flow rate of the two-dimensional gas chromatograph is 1.4–1.6 mL / min. By controlling the carrier gas flow rate within this range, the present invention can more accurately quantify the cycloalkanes content in the crude oil sample to be identified. When the carrier gas flow rate is too high, it leads to high baseline noise; when the carrier gas flow rate is too low, it leads to peak tailing or forward extension.

[0060] In a preferred embodiment, the carrier is helium. Helium has good chemical inertness, and its ionization energy of 24.6 eV is the highest among all gases. It is difficult to ionize and will not affect the chromatographic baseline due to gas flow instability. Furthermore, helium has a relative molecular mass of 4, high conductivity, and is easy to separate from other components. It has a sample enrichment effect, and its ion fragments are simple and do not interfere with the sample.

[0061] To more accurately determine the retention time of each component in a crude oil sample, in some preferred embodiments, the mass spectrometry conditions for time-of-flight mass spectrometry are as follows: mass source temperature of 230–250 °C; detection voltage of 1.8–1.85 kV; mass scan range of 40–520 amu; and desolvation gas flow rate of 500–700 L / Hr.

[0062] In a preferred embodiment, the crude oil sample to be identified has a density greater than 0.87 g / cm³. 3 The weight content of the components is 45-55 wt%. By controlling the density of the crude oil sample to be identified, this invention can further simulate and analyze the naphthenic content of medium-grade oil, verifying that the analytical method of this invention can identify naphthenic crude oil from medium-grade oil, thus solving the problem of the difficulty in accurately quantifying the naphthenic content of medium-grade oil in the prior art.

[0063] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0064] Example

[0065] In the embodiments of the present invention, the crude oil samples to be identified were taken from crude oil samples from different regions of the Junggar Basin, and the physical property data of the crude oil are shown in Table 1.

[0066] Table 1

[0067]

[0068]

[0069] Example 1

[0070] Crude oil sample preparation: 16 mg of light crude oil from the Triassic Baikouquan Formation in the Mahu area of ​​the Junggar Basin was dissolved in 2 mL of dichloromethane (chromatographic grade, CAS No. 75-09-2). Then, 20 μL of 5α-androstane standard (CAS No. 438-22-2) with a mass concentration of 0.2670 mg / mL was added to the system. The mixture was ultrasonically vibrated for 10 minutes to ensure that the 5α-androstane standard was fully mixed with the crude oil to be identified. The mixture was then allowed to stand for 0.5 hours to obtain the crude oil sample.

[0071] The above crude oil sample was injected into a two-dimensional gas chromatograph-time-of-flight mass spectrometer to obtain a three-dimensional image of the crude oil sample obtained by the two-dimensional gas chromatograph (e.g., Figure 1 As shown), and the dot matrix diagram of the full two-dimensional gas chromatograph (as shown). Figure 2 (As shown).

[0072] The mass spectrometry conditions for time-of-flight mass spectrometry are as follows:

[0073] The mass spectrometer source temperature was 240℃; the detection voltage was 1.83kV; the mass scan range was 40~520amu; and the desolvation gas flow rate was 600L / Hr.

[0074] The chromatographic conditions for the full two-dimensional gas chromatograph are as follows:

[0075] One-dimensional chromatographic column: DB-petrol column (manufacturer: Agilent), column length 60m, diameter 0.2mm, coating (100% dimethyl polysiloxane) thickness 0.25μm; temperature program: initial temperature 80℃, hold for 0.2min, increase to 290℃ at a rate of 2.5℃ / min, hold for 0.2min, then increase to 300℃ at a rate of 0.2℃ / min, hold for 10min.

[0076] Two-dimensional chromatographic column: DB-1701 column (manufacturer: Agilent), column length 4.0m, diameter 0.1mm, coating (high temperature resistant polyimide coating) thickness 0.1μm; temperature program: initial temperature 90℃, hold for 0.2min, increase to 300℃ at a rate of 2.5℃ / min, hold for 0.2min, then increase to 310℃ at a rate of 0.2℃ / min, hold for 10min.

[0077] The modulator is a dual-nozzle thermal modulator; the heating program is as follows: the initial temperature is 130℃, held for 0.2 min, then increased to 340℃ at a rate of 2.5℃ / min, held for 0.2 min, then increased to 350℃ at a rate of 0.2℃ / min, held for 10 min, and the modulator cycle is 8 s, of which 2 s is the heat blowing time.

[0078] The injection port temperature was 300℃, the crude oil sample injection volume was 1μL, helium was used as the carrier gas, and the carrier flow rate was set to 1.5mL / min.

[0079] Qualitative analysis of the retention times of different components in crude oil in a full two-dimensional gas chromatography system based on time-of-flight mass spectrometry (e.g., ...) Figure 2 As shown), based on the three-dimensional stereoscopic image of the full two-dimensional gas chromatograph (e.g. Figure 1 As shown in Table 2, the contents of n-alkanes, isoalkanes, monocyclic alkanes, bicyclic alkanes, tricyclic alkanes, tetracyclic alkanes, and pentacyclic alkanes with a signal-to-noise ratio greater than 100 in crude oil samples were quantitatively analyzed.

[0080] Table 2

[0081] Component type Component content / % n-Alkanes 23.35 Isoalkanes 25.17 Monocyclic alkanes 15.51 Bicycloalkanes 4.81 Tricycloalkane 0.48 Tetracycloalkanes 1.16 Pentacyclic alkanes 0.15 S (saturated hydrocarbons) 70.63 N (cycloalkanes) 22.11

[0082] The crude oil sample in Example 1 had an S content of 70.63 and an N content of 22.11, where S ≥ 50% and N ≤ 30%, according to... Figure 9 The crude oil type identification diagram shows that the light crude oil of the Triassic Baikouquan Formation in the Mahu area of ​​the Junggar Basin to be identified in Example 1 is paraffinic crude oil.

[0083] This invention applies the Triassic Baikouquan Formation light crude oil from the Mahu area of ​​the Junggar Basin to gasoline, kerosene, and light diesel oil, which meets the expectations for the application of paraffinic crude oil in this field and satisfies the high saturated hydrocarbon content index. This demonstrates the reliability of the paraffinic crude oil identified by this invention as a paraffinic crude oil from the Triassic Baikouquan Formation in the Mahu area of ​​the Junggar Basin.

[0084] Example 2

[0085] Preparation of crude oil samples: 25 mg of medium-quality crude oil from the Permian Lucaogou Formation in Jimsar area of ​​Junggar Basin was dissolved in 2 mL of dichloromethane (chromatographic grade, CAS No. 75-09-2). Then, 20 μL of 5α-androstane standard (CAS No. 438-22-2) with a mass concentration of 0.2670 mg / mL was added to the system. The mixture was ultrasonically vibrated for 10 minutes to ensure that the 5α-androstane standard was fully mixed with the crude oil to be identified. The mixture was then allowed to stand for 0.5 hours to obtain the crude oil sample.

[0086] The above crude oil sample was injected into a two-dimensional gas chromatograph-time-of-flight mass spectrometer to obtain a three-dimensional image of the crude oil sample obtained by the two-dimensional gas chromatograph (e.g., Figure 3 As shown), and the dot matrix diagram of the full two-dimensional gas chromatograph (as shown). Figure 4 (As shown). The chromatographic conditions of the two-dimensional gas chromatograph and the mass spectrometry conditions of the time-of-flight mass spectrometer were the same as those in Example 1.

[0087] Qualitative analysis of the retention times of different components in crude oil in a full two-dimensional gas chromatography system based on time-of-flight mass spectrometry (e.g., ...) Figure 3 As shown), based on the three-dimensional stereoscopic image of the full two-dimensional gas chromatograph (e.g. Figure 4 As shown in Table 3, the content of n-alkanes, isoalkanes, monocyclic alkanes, bicyclic alkanes, tricyclic alkanes, tetracyclic alkanes and pentacyclic alkanes with a signal-to-noise ratio greater than 100 in crude oil samples was quantitatively analyzed based on the peak area of ​​5α-androstane in the full two-dimensional gas chromatogram.

[0088] Table 3

[0089] Component type Component content / % n-Alkanes 18.28 Isoalkanes 14.20 Monocyclic alkanes 16.38 Bicycloalkanes 9.30 Tricycloalkane 3.64 Tetracycloalkanes 1.49 Pentacyclic alkanes 1.38 S (saturated hydrocarbons) 64.67 N (cycloalkanes) 32.19

[0090] The crude oil sample in Example 2 had an S content of 64.67 and an N content of 32.19, where S ≥ 50% and 30% < N < 40%, based on... Figure 9 The crude oil type identification diagram shows that the medium-quality crude oil of the Permian Lucaogou Formation in the Jimsar area of ​​the Junggar Basin in Example 2 is an intermediate-type crude oil.

[0091] This invention applies the Permian Lucaogou Formation medium crude oil from the Jimsar area of ​​the Junggar Basin to the field of lubricating oil. It meets the expectations for the application of intermediate crude oil in this field, satisfying the criteria that its composition generally includes alkanes (straight-chain, branched, and multi-branched), cycloalkanes (monocyclic, bicyclic, and polycyclic), aromatics (monocyclic and polycyclic aromatics), cycloalkyl aromatics, as well as oxygen-, nitrogen-, and sulfur-containing organic compounds and non-hydrocarbon compounds such as gums and asphaltenes. This demonstrates the reliability of the medium crude oil from the Permian Lucaogou Formation in the Jimsar area of ​​the Junggar Basin identified by this invention as medium crude oil.

[0092] Example 3

[0093] Preparation of crude oil samples: 25 mg of medium-quality Carboniferous crude oil from the Chepaizi area of ​​the Junggar Basin was dissolved in 2 mL of dichloromethane (chromatographic grade, CAS No. 75-09-2). Then, 20 μL of 5α-androstane standard (CAS No. 438-22-2) with a mass concentration of 0.2670 mg / mL was added to the system. The mixture was ultrasonically vibrated for 10 minutes to ensure that the 5α-androstane standard was fully mixed with the crude oil to be identified. The mixture was then allowed to stand for 0.5 hours to obtain the crude oil sample.

[0094] The above crude oil sample was injected into a two-dimensional gas chromatograph-time-of-flight mass spectrometer to obtain a three-dimensional image of the crude oil sample obtained by the two-dimensional gas chromatograph (e.g., Figure 5 As shown), and the dot matrix diagram of the full two-dimensional gas chromatograph (as shown). Figure 6 (As shown). The chromatographic conditions of the two-dimensional gas chromatograph and the mass spectrometry conditions of the time-of-flight mass spectrometer were the same as those in Example 1.

[0095] The content of n-alkanes, isoalkanes, monocyclic alkanes, bicyclic alkanes, tricyclic alkanes, tetracyclic alkanes, and pentacyclic alkanes with a signal-to-noise ratio greater than 100 in crude oil samples was quantitatively analyzed based on the peak area of ​​5α-androstane in the full two-dimensional gas chromatogram. The analytical results are shown in Table 4.

[0096] Table 4

[0097] Component type Component content / % n-Alkanes 2.06 Isoalkanes 4.03 Monocyclic alkanes 32.80 Bicycloalkanes 18.45 Tricycloalkane 3.47 Tetracycloalkanes 5.71 Pentacyclic alkanes 1.29 S (saturated hydrocarbons) 67.81 N (cycloalkanes) 61.72

[0098] The crude oil sample in Example 3 had an S content of 67.81 and an N content of 61.72, where S ≥ 50% and N ≥ 40%, according to... Figure 9 The crude oil type identification diagram shows that the medium-quality crude oil of the Carboniferous system in the Chepaizi area of ​​the Junggar Basin in Example 3 is a naphthenic type crude oil.

[0099] This invention applies medium-grade Carboniferous crude oil from the Chepaizi area of ​​the Junggar Basin to the field of aviation and rocket fuels. It meets the expectations for the application of naphthenic crude oil in this field and satisfies the characteristics of low pour point, good solubility, strong thermal stability and good rubber compatibility. This demonstrates that the medium-grade Carboniferous crude oil from the Chepaizi area of ​​the Junggar Basin identified by this invention as naphthenic crude oil is reliable.

[0100] Example 4

[0101] Preparation of crude oil samples: 28 mg of Jurassic Qigu Formation ultraheavy crude oil from the Fengcheng area of ​​the Junggar Basin was dissolved in 2 mL of carbon disulfide (chromatographic grade, CAS No. 75-09-2). Then, 20 μL of 5α-androstane standard (CAS No. 438-22-2) with a mass concentration of 0.2670 mg / mL was added to the system. The mixture was ultrasonically vibrated for 10 minutes to ensure that the 5α-androstane standard was fully mixed with the crude oil to be identified. The mixture was then allowed to stand for 0.5 hours to obtain the crude oil sample.

[0102] The above crude oil sample was injected into a two-dimensional gas chromatograph-time-of-flight mass spectrometer to obtain a three-dimensional image of the crude oil sample obtained by the two-dimensional gas chromatograph (e.g., Figure 7 As shown), and the dot matrix diagram of the full two-dimensional gas chromatograph (as shown). Figure 8 (As shown). The chromatographic conditions of the two-dimensional gas chromatograph and the mass spectrometry conditions of the time-of-flight mass spectrometer were the same as those in Example 1.

[0103] The content of n-alkanes, isoalkanes, monocyclic alkanes, bicyclic alkanes, tricyclic alkanes, tetracyclic alkanes, and pentacyclic alkanes with a signal-to-noise ratio greater than 100 in crude oil samples was quantitatively analyzed based on the peak area of ​​5α-androstane in the full two-dimensional gas chromatogram. The analytical results are shown in Table 5.

[0104] Table 5

[0105]

[0106]

[0107] The crude oil sample in Example 4 had an S of 35.93 and an N of 34.89, where S < 50% and N ≥ 25%, according to... Figure 9 The crude oil type identification diagram shows that the superheavy crude oil of the Qigu Formation of the Jurassic in the Fengcheng area of ​​the Junggar Basin in Example 4 is an aromatic-cycloane type crude oil.

[0108] This invention applies the Jurassic Qigu Formation superheavy crude oil from the Fengcheng area of ​​the Junggar Basin to the fields of power generation and new material processing. It meets the expectations for the application of aromatic-cycloane type crude oil in this field, satisfying the indicators of high density, high viscosity, high gum content, low wax content, and low pour point. This demonstrates that the superheavy crude oil from the Jurassic Qigu Formation in the Fengcheng area of ​​the Junggar Basin identified by this invention as aromatic-cycloane type crude oil is reliable.

[0109] Comparative Example 1

[0110] The critical fraction method was used to analyze the medium-quality crude oil of the Permian Lucaogouquan Formation in the Jimsar area of ​​the Gar Basin and the medium-quality crude oil of the Carboniferous Formation in the Chepaizi area of ​​the Junggar Basin. The process was as follows: Crude oil samples of the same weight as those in Examples 2 and 3 were weighed. 30 ppm of demulsifier (polyether demulsifier) ​​and softened water were added to the crude oil samples of Examples 2 and 3, respectively. Then, a high-voltage electric field (electric field strength 1.5 kV / cm, energized for 10 minutes) was applied to cause the salt-containing water droplets to aggregate and settle, thereby removing salt, water and other impurities from the crude oil. The pretreated crude oil of Examples 2 and 3 was heated and sent to the primary distillation column of an atmospheric distillation unit to distill off most of the light gasoline. The crude oil at the bottom of the primary distillation column was heated to 370°C, and the density of the first critical fraction was tested. Then, under an absolute pressure of about 6 kPa, the temperature was raised to 500°C, and the density of the second critical fraction was tested.

[0111] The densities of the first and second critical fractions of the crude oil sample in Example 2 were tested and found to be 0.792 g / cm³. 3 and 0.857 g / cm 3 In Example 3, the densities of the first and second critical fractions of the crude oil sample were 0.799 g / cm³. 3 and 0.851 g / cm 3 It can be observed that the first and second critical fractions of both crude oils have similar densities, indicating they are the same type of crude oil, specifically intermediate crude oil. However, based on their pour points (e.g., 12, -22.4℃) and wax content (9.9, 2.14%), these two crude oils are clearly different and cannot be the same type. This demonstrates that when using the critical fraction method to determine the density of medium-quality crude oils of the same amount, it is difficult to accurately distinguish the type of crude oil and cannot reflect its true quality.

[0112] Comparative Example 2

[0113] The critical fraction method was used to analyze the Jurassic Qigu Formation ultraheavy crude oil in the Fengcheng area of ​​the Junggar Basin, and the process was the same as that of Comparative Example 1.

[0114] Based on the key fraction method analysis, the density of the first and second key fractions of the extra-heavy crude oil from the Qigu Formation of the Jurassic system in the Fengcheng area of ​​the Junggar Basin was found to be 0.898 g / cm³. 3 and 0.958 g / cm 3 The crude oil was identified as naphthenic crude. However, analysis of the physical properties of the Jurassic Qigu Formation ultraheavy crude oil from the Fengcheng area of ​​the Junggar Basin reveals that it has a high pour point of 38℃, is wax-free, and has a high viscosity of 175,800 mPa·s (50℃). This type of crude oil is of poor quality and does not meet the criteria for naphthenic crude oil. This demonstrates that the key fraction method has limited applicability and, under certain circumstances, cannot accurately reflect the true quality of crude oil.

[0115] The identification results of Comparative Examples 1 and 2 reveal that existing technologies for crude oil identification and analysis contain errors and have a narrow scope of application. In contrast, this invention, based on two-dimensional gas chromatography, can accurately quantify the cycloalkanes content in crude oil, has a wide range of applications, and can identify light crude oil as well as medium and extra-heavy crude oil.

[0116] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for identifying crude oil types based on two-dimensional gas chromatography-time-of-flight mass spectrometry, characterized in that, The method includes: Crude oil sample preparation: Dissolve the crude oil sample to be identified using a diluent, and then add 5α-androstane standard to the system to obtain the crude oil sample; Test: The crude oil sample was subjected to two-dimensional gas chromatography-time-of-flight mass spectrometry (GC-MS / MS). The peak positions of 5α-androstane, n-alkanes, isoalkanes, monocyclic alkanes, bicyclic alkanes, tricyclic alkanes, tetracyclic alkanes, and pentacyclic alkanes in the crude oil sample were qualitatively determined based on the time-of-flight mass spectrometry. The content of n-alkanes, isoalkanes, monocyclic alkanes, bicyclic alkanes, tricyclic alkanes, tetracyclic alkanes, and pentacyclic alkanes with a signal-to-noise ratio greater than 100 in the crude oil sample was quantitatively analyzed based on the peak area of ​​5α-androstane in the GC-MS. Identification: The ratio of the sum of the weights of the n-alkanes, isoalkanes, monocyclic alkanes, bicyclic alkanes, tricyclic alkanes, tetracyclic alkanes, and pentacyclic alkanes in the crude oil sample to the weight of the crude oil sample to be identified is denoted as S; the ratio of the sum of the weights of the monocyclic alkanes, bicyclic alkanes, tricyclic alkanes, tetracyclic alkanes, and pentacyclic alkanes in the crude oil sample to the weight of the crude oil sample to be identified is denoted as N; When S≥50% and N≤30%, the crude oil sample to be identified is paraffinic crude oil; When S≥50% and 30%<N<40%, the crude oil sample to be identified is intermediate crude oil; When S≥50% and N≥40%, the crude oil sample to be identified is a naphthenic crude oil. When S < 50% and N < 25%, the crude oil sample to be identified is an aromatic-asphalt type crude oil. When S < 50% and N ≥ 25%, the crude oil sample to be identified is an aromatic-cycloalkane type crude oil.

2. The method for identifying crude oil types based on two-dimensional gas chromatography-time-of-flight mass spectrometry according to claim 1, characterized in that, In the preparation of the crude oil sample, the weight of the crude oil sample to be identified is 5-15 mg per 1 ml of the diluent.

3. The method for identifying crude oil types based on two-dimensional gas chromatography-time-of-flight mass spectrometry according to claim 1, characterized in that, In the preparation of the crude oil sample, the weight of the 5α-androstane standard is 0.001~0.01 mg per 1 ml of the diluent.

4. The method for identifying crude oil type based on full two-dimensional gas chromatography-time-of-flight mass spectrometry according to any one of claims 1 to 3, characterized in that, The diluent is selected from n-hexane and / or dichloromethane.

5. The method for identifying crude oil types based on two-dimensional gas chromatography-time-of-flight mass spectrometry according to claim 4, characterized in that, The diluent is selected from dichloromethane.

6. The method for identifying crude oil type based on full two-dimensional gas chromatography-time-of-flight mass spectrometry according to any one of claims 1 to 3, characterized in that, The two-dimensional gas chromatograph has two columns with different polarities, each independently selected from either a DB-Petro column or a DB-17HT column; The detector of the full two-dimensional gas chromatograph is a hydrogen flame ionization detector; The modulator of the full two-dimensional gas chromatograph is a dual-nozzle thermal modulator; the modulation period of the modulator is 8.0~10.0s, and the hot blowing time is 2.0~3.0s.

7. The method for identifying crude oil types based on two-dimensional gas chromatography-time-of-flight mass spectrometry according to claim 6, characterized in that, The DB-Petro column has a length of 50-60m, an outer diameter of 0.2-0.3mm, an inner diameter of 0.1-0.2mm, and a coating thickness of 0.1-0.5μm; the DB-17HT column has a length of 2.5-3.0m, an outer diameter of 0.1-0.2mm, an inner diameter of 0.1-0.2mm, and a coating thickness of 0.1-0.5μm.

8. The method for identifying crude oil type based on two-dimensional gas chromatography-time-of-flight mass spectrometry according to claim 6, wherein the one-dimensional column of the two-dimensional gas chromatograph is the DB-Petro column and the two-dimensional column is the DB-17HT column; the temperature program of the one-dimensional column is as follows: hold at an initial temperature of 60~80℃ for 0.1~0.2 min, increase the temperature to 290~300℃ at a rate of 2~3℃ / min, hold for 0.1~0.2 min, and then increase the temperature to 300~310℃ at a rate of 0.1~0.2℃ / min, hold for 8~10 min; The temperature program for the two-dimensional chromatographic column is as follows: hold at an initial temperature of 70~90℃ for 0.1~0.2 min, increase the temperature to 300~310℃ at a rate of 2~3℃ / min, hold for 0.1~0.2 min, and then increase the temperature to 310~320℃ at a rate of 0.1~0.2℃ / min, hold for 8~10 min. The modulation and heating program is as follows: hold the initial temperature of 120~130℃ for 0.1~0.2 min, raise it to 330~350℃ at a rate of 2.0~3.0℃ / min, hold it for 0.1~0.3 min, raise it to 340~360℃ at a rate of 0.2℃ / min, hold it for 10 min, and the modulator cycle is 7~9s, of which 1~3s is the heat blowing time.

9. The method for identifying crude oil types based on two-dimensional gas chromatography-time-of-flight mass spectrometry according to claim 6, characterized in that, The injection port temperature of the full two-dimensional gas chromatograph is 300~310℃.

10. The method for identifying crude oil types based on two-dimensional gas chromatography-time-of-flight mass spectrometry according to claim 9, characterized in that, The injection volume of the crude oil sample is 1.0~1.2 μL.

11. The method for identifying crude oil types based on two-dimensional gas chromatography-time-of-flight mass spectrometry according to claim 6, characterized in that, The carrier gas flow rate of the two-dimensional gas chromatograph is 1.4~1.6 mL / min.

12. The method for identifying crude oil types based on two-dimensional gas chromatography-time-of-flight mass spectrometry according to claim 11, characterized in that, The carrier gas is helium.

13. The method for identifying crude oil type based on full two-dimensional gas chromatography-time-of-flight mass spectrometry according to any one of claims 1 to 3, characterized in that, The crude oil sample to be identified has a density greater than 0.87 g / cm³. 3 The weight content of the component is 45~55wt%.

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